Calling for gasification accident cases! (Please ask the moderator for support)

Just trying to spark some discussion! System shutdown caused by issues with the burner cooling water. 1 Time: ×× year ×× month ×× day. 2 Accident details: On ×× month ×× day, the burner cooling water tank overflowed; the dispatcher on site instructed the operators to take action. At around 10:30, while recording data in the control room, it was found that there was no liquid level in the burner cooling water tank, the flow rate of water used for cooling the burners was zero, the return water temperature was 35°C, and the standby pump for the burner cooling water pump had started automatically. Upon on-site inspection, it was found that the valve for adding water to the burner cooling water tank was almost completely closed. The outlet pressure of the cooling water pump for burner A# was 2.4 Mpa, while the outlet pressure of pump B# was 0.7 Mpa. The operators immediately added water to the cooling water tank. 10 minutes later, the safety system triggered a shutdown due to the lack of cooling water for the burners. 3 Accident losses: The burner cooling water coil was damaged, resulting in a 5 hours and 14 minutes shutdown of the system. 4 Accident category: General process operation accident. 5 Causes of the accident: 5.1 The make-up water valve for the burner cooling water tank was closed, resulting in a lack of water in that tank; this was the main cause of the accident ； 5.2 The operators lack a sense of responsibility, fail to keep records and reports in a timely manner, and do not conduct thorough on-site inspections, resulting in the failure to identify potential accident hazards in a timely fashion ； 5.3 Excessive invalid alarm signals from the computer led the operators to become careless, preventing them from detecting in time the alarm indicating low flow rate of the burner cooling water, which resulted in delayed intervention. 6 Lessons from Accidents and Preventive Measures: 6.1 Operators should identify key aspects during on-site inspections to ensure the quality of these inspections ； 6.2 Strengthen workshop process management; operators should record operation reports on time and conduct inspections regularly, so as to identify any issues in the production system promptly ； 6.3 Strengthen the education on employees’ sense of responsibility; operators must verify each alarm signal generated by the computer carefully and not take it lightly ； 6.4 Eliminate alarm signals in the computer that are unrelated to process operations.

One more! The motor of the circulation pump in Tower A suffered damage due to water entering it, which caused the system to shut down. Time: 2. Incident details: The crew tested the repaired circulation pump in Tower A#. They first conducted a thorough inspection of the pump, including checking the root valve on the pump’s inlet pipeline using a wrench. When the ball valve at the pump inlet was opened, a large amount of black water sprayed out from the root valve in the inlet pipeline, causing the motor of the operating B# washing tower circulation pump to be damaged by water ingress, which led to a disruption in the supply of quench water to the B# gasifier. At 17:36, a low liquid level in the gasification furnace caused the gasification unit to shut down in a cascade shutdown. 3 Accident losses: The motor of the washing tower circulation pump was damaged, resulting in a 5-hour shutdown of the system. 4 Accident category: General process operation accident. 5 Causes of the accident: 5.1 The operator lacked a sense of responsibility; although the valves that needed to be checked before starting the machine were indeed checked, the verification was not thorough enough ； 5.2 The waterproofing of the motor wiring box is inadequate, resulting in water entering the motor ； 5.3 The workshop’s process management is inadequate, and the ticket inspection system is not properly implemented. 6 Lessons from Accidents and Preventive Measures: 6.1 For the start-up, shutdown, and testing of operating equipment, the ticketing system must be strictly followed, with each step being implemented carefully ； 6.2 Strengthen the cultivation of employees’ sense of responsibility and improve their professional competence ； 6.3 Modify the waterproofing of the motor junction box.

Incomplete pipe flushing led to burns on the cleaner’s face. 1. Date: ×× year ×× month ×× day. 2. Incident details: On ×× month ×× day, a leakage occurred in the seal of the slag discharger in one of the vaporization units, which forced that unit to be shut down for repairs. During the pressure relief process, the water flowing into the high-pressure flash tube of the vaporization unit was directed into the start-up cooler (to prevent pressure from building up). This water also flowed into the sedimentation tank. When attempting to open the ball valve leading to the start-up cooler, no liquid flowed through; even using flushing water did not help. The site supervisor ordered that the check valve located behind the ball valve be inspected to determine if it was blocked. Upon opening the check valve, it was found to be intact. It was then determined that the blockage was located at the joint between the check valve and the ball valve. As a result, a cleaner was assigned to clean the area using high-pressure flushing water. To save time, the flushing was carried out directly through the check valve without first closing the ball valve. A few minutes after starting the flushing, the pipeline became unobstructed, and the steam inside the pipeline escaped rapidly, causing severe burns to the operator’s face (pressure: 3.0 MPa, temperature: around 250 degrees). 3. Hazards of the accident: Causes severe burns to the operator’s face. 4. Accident category: Level 3, mild. 5. Cause of the accident: 5.1 Poor performance by the operator, who failed to thoroughly clean the pipes after use last time; this led to pipe blockage and was the main cause of the accident. 5.2 The cleaning staff lack safety awareness and proceed with operations without ensuring safety first. 5.3 Illegal instructions from on-site supervisors, who give such instructions in an attempt to save time. 6. Lessons learned from accidents and preventive measures: 6.1. Strengthen safety education for employees. 6.2 Increase the sense of responsibility among operators. 6.3 Improve the technical skills of on-site supervisors to avoid giving orders blindly.

A four-nozzle gasification accident occurred due to an installer mistakenly shutting off the power supply, which caused one pair of burners to stop operating. 1. Time: 9:00 on XX/XX/XX. 2. Accident details: Electrical installers at X Chemical Construction Company, while connecting the power supply to the auxiliary equipment of the slurry feed pump in the C gasification furnace system, cut off the power to the auxiliary equipment (lubrication oil and drive fluid pumps) of the operating D# slurry feed pump. As a result, the D# slurry feed pump stopped working, and burners G and H also ceased operation. 3. Accident loss: The B# gasifier operated with a single burner for 100 minutes. 4. Accident category: Minor accident. 5. Cause of the accident: (1) The installation workers from X Chemical Construction failed to obtain the necessary permits and did not consult the relevant authorities before starting work on the already in-use power distribution facilities; this constituted serious violations of safety procedures. (2) The labels inside the distribution panel are unclear, and no warning signs have been installed. 6. Lessons from the accident: Relevant permits must be properly obtained during maintenance or installation, and safety procedures must be followed. 7. Preventive measures: (1) Strictly enforce safety regulations for electrical work; when working on systems that are already in operation, comply strictly with the relevant permits, and ensure that they are signed off by authorized personnel. (2) Provide safety training for maintenance and installation personnel; they may only start working after passing the examination. (3) Provide wiring diagrams in the distribution panel and label them.

The shutdown of the gasification high-pressure slurry pump led to a system stoppage. 1. Time: × year × month × day. 2. Incident details: After the gasification system was brought online and stabilized, at 1:20, the process operator on shift discovered a high pressure difference across the lubricating oil filter of the high-pressure slurry pump. He reported this to the shift supervisor, team leader, and the workshop duty officer. After conducting an on-site inspection, the duty officer instructed the operator to monitor the pump’s operation. At 5:50, the high-pressure coal slurry pump tripped due to low oil pressure, causing the ammonia synthesis system to shut down. 3. Accident losses: The production system was shut down for 17 hours, resulting in a reduction in synthetic ammonia production of 135 tons. 4. Accident category: General process accident. 5. Cause of the accident: (1) The lubricating oil filter was clogged, resulting in a high pressure difference before and after the filter, which was the main cause of the accident ； (2) The workshop duty personnel, upon receiving notification of potential accident hazards, did not know how to handle them and failed to contact the relevant personnel for assistance, which was the direct cause of the accident. 6. Lessons learned from accidents and preventive measures: (1) Proactively address potential hazards associated with various types of backup vehicles ； (2) Strengthen workshop process management and further clarify the responsibilities of various personnel ； (3) Strengthen professional training to improve employees’ capabilities in handling various types of accidents, so that they can truly recognize the losses caused by such accidents to both the enterprise and individuals.

This post was last edited by Qingfeng Yao Mingyue on 2009-5-10 at 10:30. Fluctuations in coal slurry caused the system to shut down, stop operating, or operate at reduced capacity. 1. Date: × year × month × day. 2. Incident details: The gasifier stopped operating due to issues with the air separation unit; during the process of restarting the gasification unit, it was found that the coal slurry circulation pipeline was blocked by ice, so it was cleared and flushed. After the pipeline was cleared, at 9:48, the gasification furnace was successfully started in conjunction with the other systems, and the system came online. At 15:42, the chief operator in the control room noticed a decrease in the slurry flow rate and instructed the personnel on site to check the slurry pipelines. The on-site operators and workshop supervisors promptly went to the site to inspect the slurry pipeline and found that slurry was leaking from the wash water backflow valve in front of valve 01, the slurry cut-off valve on the ninth floor. To prevent explosion accidents caused by peroxides, the rear system was forced to shut down under gas pressure; after the vaporization system was brought to its minimum load, the backflow valve was closed, and the rear system was restarted. 3. Accident losses: The system was shut down due to a gas loss for 5 hours and 5 minutes. 4. Accident category: General process operation accident. 5. Cause of the accident: (1) During driving, the operator failed to verify the valve as required by the operation procedure, which was the main cause of the accident ； (2) The process technicians failed to provide clear handover of the production status ； (3) The operator lacked a sense of responsibility and failed to verify or report on this valve ； (4) The workshop’s process management is inadequate, with insufficient supervision over the start-up material feeding confirmation forms. 6. Lessons learned from the accident and preventive measures: (1) The ticketing system must be strictly followed when driving, and each item specified in the tickets must be verified one by one ； (2) Strengthen workshop process management and enforce strict shift handovers ； (3) Strengthen the education on employees’ sense of responsibility and improve their awareness of safe production ； (4) Address new freezing-related issues that arise during winter prevention efforts, formulate preventive and corrective measures, and organize staff training to prevent similar accidents from occurring.

1. Time of the accident: 14:01 on XX, XX, 2006. 2. Accident details: At that time, Pump B of the washing cycle was under maintenance due to a mechanical seal leak, and its pump body was removed. Before resetting, the equipment operator wanted to flush the inlet filter; they informed the control operator to open inlet valve B, and washing water at a pressure of ~3.8 MPa and a temperature of ~160°C was discharged, causing the low liquid level interlock in the washing tower to activate and shutting down the unit. No injuries were reported in this accident. According to the footage of the accident, several workers were working near the nozzle before the wash water was ejected. 3. Cause of the accident a) Immediate cause: Instruction error. When the pump body is not reset and the inlet pipe is open, the equipment operator is authorized to issue instructions to open the valve and flush the filter. b) Direct cause: Operational error. The main control operator mechanically carried out a command from a non-direct superior to open the valve and flush the filter while the pump body had not been reset and the inlet pipe was open. c) Indirect cause: Inadequate implementation of safety measures for shutdown maintenance. Due to repeated maintenance, the inlet switch valve was not locked according to the prescribed procedure during the third reset (by shutting off the gas supply and removing the fuse), thus failing to achieve the intrinsically safe level of \"fail-safe\" operation. d) Indirect cause: Carelessness. During the testing phase, it was common to open the inlet valve to flush the inlet pipeline or filter, and this became a habit; as a result, this practice of using the inlet valve for flushing was continued even during normal production. 4. Lessons from accidents and preventive measures a) Raising the safety awareness of operators is an important means of preventing accidents. Operators must always consider the safety conditions in the event of failures in various equipment and facilities or human operational errors, and take measures to ensure \"fail-safe\" and \"fault-safe\" operations, so as to keep the production process as well as the equipment and facilities in a safe state. b) To prevent similar accidents from occurring, a maintenance operation ticket for the circulation pump was prepared, with each step of the operation being carried out and verified one by one. Special emphasis is placed on shutting off the instrument air supply or instrument power supply for the control valves. c) Many cut-off valves in the gasification section are automatic valves; during daily operations, it is necessary to pay attention to shutting off the instrument air supply or power supply (paying attention to the “FO” and “FC” states of the valves), as this is the only way to prevent accidental operations. d) Thereafter, a stop valve was installed at the inlet of the circulation pump.

1. Time of the accident: XX/XX/20XX. 2. Course of the accident: The operator, during his routine inspection, detected a leak at the flange of the cooling water flow meter for the coal burner; he immediately reported this to the shift leader, who ordered that repairs be carried out to tighten the connection. During the tightening process by the maintenance personnel, the interlock device came into action, causing the continuous operation to be interrupted. 3. Cause of the accident: It was mainly due to a lack of understanding; this flow meter uses vortex flow measurement technology and is quite sensitive to vibrations. The handling was improper. 4. Lessons from accidents and preventive measures: Hazard identification should be thorough, and preventive measures must be in place

This post was last edited by Tianya Langji on 2009-5-10 at 15:13. 1. Time of the accident: around 16:00 on XX, X, 20XX. 2. Course of events: That afternoon, the on-site construction workers from XX Company, carrying a written work order, installed a blind flange at the lower opening (φ250) of the sampler located in the coal grinding frame ash bin. No preventive measures were taken; the removal of the blocking plates led to a massive release of coal dust, which covered the sky and was truly terrifying. Immediately after the coal dust leakage, request fire trucks to spray water at the scene and inform people to evacuate ； Brave personnel were organized to seal the leak, and the sealing was successful after about 30 minutes. About a hundred tons of coal powder leaked. All the commando soldiers involved in the rescue operation turned black, with eyes and teeth that were particularly white. 3. Preliminary analysis of the cause of the incident: Direct cause: The construction workers took no measures to remove the blocking plates. Indirect cause: a. The coal powder sampler was selected with an oversized size; its spiral structure is unable to prevent the leakage of coal powder, thus posing a potential risk of leakage. b. A lack of understanding of the flow properties of pulverized coal and insufficient awareness of its hazards are also causes of accidents. 4. Preventive measures: Improve the sampler and restore the design by installing thin-cut-off valves to meet the basic requirement of allowing flow during sampling and shutting it off when not sampling. Conduct a thorough inspection and evaluation of other similar samplers to prevent similar incidents from occurring again. Standardize the procedures for adopting low-standard temporary measures.

A temporary worker washing the floor caused the coal mill to shut down, and the low insulation level of the motor prevented it from operating. 1. Date: × year × month × day. 2. Incident details: After the ball mill was started up, at 23:15, a temporary worker was washing the floor with water; wastewater spilled into the control room, which led to the shutdown of the coal mill. Due to the low insulation level of the motor, it was not possible to restart it, and the gasification system had to be stopped at 6:10 on the 15th. 3. Accident losses: 90 tons less synthetic ammonia were produced, and startup and shutdown costs increased. 4. Accident category: General equipment accident. 5. Cause of the accident: (1) The temporary workers lacked safety awareness; flushing the floor with water caused wastewater to splash into the control room, resulting in a shutdown of the system and low insulation of the electrodes ； (2) The control room is located in an inappropriate position; the doors do not close properly, and its waterproofing performance is poor ； (3) The workshop failed to manage temporary workers properly, with no supervision in place. 6. Lessons learned from the accident and preventive measures: (1) Strengthen education and management of temporary workers; when they work in critical areas, they must be supervised by someone ； (2) Carry out technical upgrades to the coal mill control cabinet and add waterproof protection facilities ； (3) Slurry control after the sudden shutdown of the coal mill shall be addressed through research by the workshop and relevant departments.